GPS Mapping Apps

Just got a Microsoft 640 and tried to download the Viewranger app. Wouldn't work. So I tried the Ordnance Survey app and that didn't work either. Both these apps use OS maps and GPS to pinpoint exactly where you are in remote areas. Am I doing something wrong? If the phone doesn't support these apps does anyone know of a GPS/OS mapping app that is supported by the 640. Many thanks.

What do you mean by didn't work? You mean it wouldn't download? Or it didn't function after you downloaded it? That point is a bit unclear to me.

If your device isn't compatible, the store shouldn't let you download it, so it is a matter of finding one that is through the Windows Phone store. If you're trying to download through some source other than the Windows Phone Store, then that's the problem. Use the Store app installed on your phone to do the searching for the app. It will save time.

There is one called Off-Grid GPS that seems to be pretty good, but I'm not sure if it has all the features you're looking for.